Airframe and Powerplant

Bucket Brigade

May 1, 2000

ByPeter A. Bedell

Spring's here and your airplane is filthy

If you can escape the spring-cleaning chores at home, it's time to head out to the airport and spruce up the airplane for the upcoming busy summer flying season. But washing the airplane goes beyond just making it look pretty. Washing your airplane is about the only other time (besides the annual inspection, perhaps) that the airplane gets a thorough visual once-over. During a wash job, you're likely to find a missing screw or two, popping rivets, cracks, corrosion, fuel-cell leaks, missing cotter pins, and more. Ever tried to look for cracks in a dirty landing gear casting? You won't find them.

Think of this often-filthy job as an opportunity to give the airplane a very thorough preflight that happens to make it look good as a result. It is for this reason that washing the airplane yourself is a very good idea. Although some are savvy enough to note problems with your airplane, the typical airplane washer at the FBO may not be well versed enough in airplanes to have his interest piqued by a spot of corrosion or a missing screw.

Preparations

Start with the site of your scrub job. A smooth-floor hangar with a drain is the best option. The hangar provides the critical shade needed to eliminate spots created when the sun dries water beads onto the surface. This also negates the need for constant rinsing to avoid soap drying onto the surface. The best part about a nice hangar is that you can also cruise around on a creeper on the smooth floor for easy cleaning and scrubbing of the airplane's underside. If such a site isn't available, try to do the job on an overcast or even rainy day. If the wash is to be done outside on a sunny day, wash small segments of the airplane at a time so that you don't allow any soap to dry to the finish.

You should also prepare the airplane by inserting cowl plugs and pitot covers and taping over static ports and other portals. Taping over the static port(s) is especially important in cold weather, when water can freeze in the static system. Just don't forget to remove it.

Gather up a bucket, some clean towels, soft brushes, and even a dust mop. Airplane paint is pretty tough stuff, but you don't want to test a $7,000 paint job's durability with a hard-bristle brush that removes the paint along with the bugs and grease. The dust mop is great for large-area light-duty cleaning such as the top and bottom of the wings. Smaller towels can be used for the detail work, and the brushes can be used on the belly and bugs. Sponges can be used in a pinch, but care should be taken so that deposits don't get trapped in the porous surface and dragged all over the airplane, leaving scratches in their wake.

Degrease and debug

Call me a masochist, but when I wash an airplane, I like to start with the hardest parts first. In most cases, removing the splattered remains of bugs from the leading edges and cutting through the mixture of oil, exhaust, and grime that collects on the belly of the airplane are the most tedious and unrewarding parts of washing an airplane. You can spend hours working on bug removal and barely see the fruits of your labor. Likewise, degrease the belly and nobody can tell that you did any good unless you make them crawl on their hands and knees. After all those hours, it seems you've gotten nowhere. But, with these two tasks out of the way, you're well more than halfway to a beautiful airplane again.

So far, the best product I've used to remove bugs is Knight's Spray Nine. This cleaner is available for a reasonable price from most auto-parts stores and is claimed to be a multipurpose cleaner that also happens to kill HIV. I can't tell you what ingredient in the product makes it so effective on bugs, but I find that if you spray the mixture on a bug-soaked leading edge, it begins to dissolve the remains in seconds, allowing you to wipe away the bugs with a minimum of rubbing. Since much of my flying is in and out of grass runways, Spray Nine has become a much-appreciated timesaver when it comes time to remove the bugs. Is it safe? In the many years that I and my flying buddies have used the product, we've seen no ill effects on airplanes painted with Sherwin Williams' (formerly Pratt & Lambert's) Jet-Glo and Acry-Glo paints, as well as other airplanes painted with Sikkens products and DuPont's Imron. I do, however, make it a practice not to allow Spray Nine to sit on an airplane for long periods of time without being wiped off thoroughly. The product continues to work well, perhaps better, when diluted 1:1 with water.

After the bugs are removed, I usually head for the belly. The aforementioned creeper is important for this job, as much for your sanity as for your back. A pair of shop goggles and dishwashing gloves also should be used. (No one said being a pilot is glamorous.) Since you are on your back spraying chemicals upward at the belly, it is quite obvious why you should wear eye protection. Although it's not the typical rule when washing an airplane overall, I like to start at the lowest point of the belly and work upward toward the tail to reduce the amount of runoff that will drip from the belly onto me.

Products like Arrow Magnolia's Carbon-X or Tomar Industries' TR-1000 will cut through caked-on exhaust stains quite well. Both of these products are designed for use on aircraft, so there's no need to worry about damage to bare aluminum surfaces. Zep also makes good cleaning products, but these are typically only available in bulk for consumption by FBOs. Home Depot and other home-improvement stores carry several cleaning products in bulk.

There also are products available from the grocery or auto-parts store such as Simple Green, an environmentally safe cleaner. Simple Green does an admirable cleaning job for a fraction of the cost of the aviation cleaners. (The major reason for the cost difference is hazmat fees for shipping the aviation cleaners to your home.) Most of these products can be diluted with water for use on parts of the airplane that don't need the full strength of the cleaners. When buying nonaviation cleaners, always check the labels for warnings regarding use on aluminum and painted surfaces.

When washing under the belly, try to avoid spraying strong solvents near landing-gear lube points and wheel bearings. Cleaning solvents are designed to cut through grease and will remove the protective layer of lubricant between these expensive moving parts. Also use great care around such areas when using a pressure washer because water can be forced into crevices, pushing out the grease and accelerating corrosion.

Airplanes typically have several holes in the skin at low points of the airframe to evacuate water and moisture that accumulates inside the airframe. Trapped moisture acts as an accelerant to corrosion. Keeping the holes clear allows moisture to drain away and dry air to circulate through that portion of the airframe. Have a long, skinny tool or reamer handy to clear the mud, dirt, mud daubers, or other contaminants from the holes.

Get off your back

After the belly and bugs, it's time to get off your back, remove the goggles, and move to the parts of the airplane that people actually see. I like to take a quick scan for bird droppings on the top surfaces. Bird droppings are very acidic and can eat through paint finishes. As mentioned before, airplane paint is pretty tough, but some bird species' droppings are too. And if the stuff sits for a long time, don't be surprised to see some finish damage. For the stubborn droppings, soak a towel or washcloth in soapy water and place the dripping-wet towel on the mess and leave it while you work on the rest of the airplane. After several minutes, the droppings should lose most of their tenacious grip on the finish, making cleanup relatively easy.

Like washing your car, it's best to start at the top and work down. So get out the ladder and start at the top of the tail or the top of the wings (taildraggers, high wings). Here a long mop handle can come in real handy to avoid having to climb a ladder while wearing wet shoes in the proximity of an expensive airplane. Avoid the windows with your mops, brushes, towels, or whatever you're using. Trapped dirt in these cleaning utensils can scratch a window very easily. It's best to leave the windows as one of the final steps in cleaning the airplane. Cleaning windows is the subject of an entire article itself (see "Airframe and Powerplant: Per-plex'd," May 1999 Pilot). In general, when cleaning windows you want to use lots of water, clean towels, and mild cleaners.

Do sections of the airplane at a time to be sure you don't miss anything, and so that soap doesn't have a chance to dry to the surface. Rinse often and generously. For large-area surfaces (the top of the wings, for example) that are lightly soiled, the mop will do a good job very quickly. Harder-to-reach areas can be hit with a small towel, and the detail work can be done with a washcloth.

If you have the time and a show-like finish is what you are after, you can dry the airplane with a reusable chamois cloth or something similar. Following that up with a clean bath towel will remove the rest of the residue quite nicely.

The amount of detail work is up to you. I like to go over the landing gear thoroughly, while others might want to spend the time polishing spinners or polishing off oxidized paint. Spinner polishing is a laborious job that can be done by hand with a healthy dose of elbow grease. After doing the job and seeing how fast a pretty spinner goes ugly, you'll know why some people simply paint them. Airplanes with deice boots add another step of work to the job. So far the best product we've used on boots is PBS made by Jet Stream. BFGoodrich's Icex is reportedly very good at making boots more efficient in removing ice while making them look nice.

The best part

Like most pilots, you probably look for any excuse to fly. I typically forgo the towel-drying routine in favor of a 120-knot blow-drying job. Quite honestly, the best way to remove the standing water from on and inside the airplane is to take it for a flight. Besides, you just did one of the most-thorough preflight routines since your first checkride. Be sure to thoroughly drain fuel from the sumps, keeping a sharp eye out for water that may have made it past the fuel caps and seals. And don't forget to remove the tape from the static ports. It's also a good idea to make sure that the landing gear and control surfaces are still adequately lubed.

If you can't fly the airplane after the wash, make it a point to move all of the control surfaces through their full travel to evacuate trapped water. Also try to change the airplane's attitude on the ground by pushing down on the tail on a tricycle-gear airplane, for example. This will hopefully force trapped water toward a drain hole in the airframe.

Now that the airplane is dried, you'll be ready to break out the wax, right? Unfortunately, that's another story — and another weekend day.

The products mentioned in this article are by no means a comprehensive listing of all cleaning products available to wash an aircraft. We simply mentioned products that we have used with good results. BFGoodrich's Icex is available by calling suppliers such as Aviall (800/284-2551). Jet Stream products are available by calling (800/727-5387 or 214/351-3400). Tomar Industries can be reached at 919/467-0362. Arrow-Magnolia's Carbon X is available through Sporty's Pilot Shop by calling 800/SPORTYS. Simple Green and Spray Nine can be found in auto-parts, home-improvement, or grocery stores.